Field of the Invention:
The present invention relates to a heating device which uses a laser beam and, more particularly, to a heating device for heating a region to be heated in a predetermined temperature range.
Description of the Prior Art:
The laser beam has recently been used for heat treatment of metal and a softening process for glass, quartz and the like. In this case, the spot diameter of the laser beam is generally relatively small. When the heated region is large, the heated region must be reciprocally scanned by the laser beam for heating.
As a method in which the heated region is reciprocally scanned by the laser beam for heating, one method is conventionally adopted in which a laser beam is radiated on an object to be heated through a reflecting mirror, and the reflecting mirror is oscillated at a constant amplitude and frequency so that the laser beam which is incident moves reciprocally.
However, when the reflecting mirror is simply oscillated as described above, the heated region may not be uniformly heated. For this reason, if uniform heating is required, for example, Japanese Laid-Open Patent Application 54-101576 proposes that the power of the laser beam be changed in response to the displacement of the reflecting mirror. However, changes in the power of the laser beam may not easily be accomplished and this device entails higher cost.